Predisposing factors for small colon impaction in horses and outcome of medical and surgical treatment: 44 cases (1999-2004)

OBJECTIVE: To identify factors associated with development of small colon impaction in horses and with selection of medical versus surgical treatment and to determine the prognosis for affected horses following medical or surgical management. DESIGN: Retrospective case series. ANIMALS: 44 horses with primary impaction of the small colon. PROCEDURES: Medical records were reviewed for signalment, history, clinical findings, treatment (medical vs surgical), hospitalization time, and outcome. For comparison purposes, the same information was collected for 83 horses with primary impaction of the large colon. RESULTS: Diarrhea was the only factor found to be associated with development of small colon impaction. Horses with small colon impaction were 10.8 times as likely to have diarrhea at the time of initial examination as were horses with large colon impaction. Abdominal distension was the only factor associated with use of surgical versus medical treatment. Horses with small colon impaction that were treated surgically were 5.2 times as likely to have had abdominal distension at the time of admission as were horses with small colon impaction that were treated medically. Overall, 21 of 23 (91%) horses treated medically and 20 of 21 (95%) horses treated surgically survived to discharge. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that diarrhea may be a risk factor for development of small colon impaction and that horses with small colon impaction that have abdominal distension at the time of initial examination are more likely to require surgical than medical treatment.     

Matrix metalloproteinase-9 in laminae of black walnut extract treated horses correlates with neutrophil abundance

We sought to determine whether a correlation exists between neutrophil infiltration and tissue matrix metalloproteinase-9 (MMP-9) content in digital laminae collected during the prodromal and acute phases of laminitis in horses treated with an aqueous black walnut heartwood extract (BWE). Hoof laminar tissue was obtained at the onset of leukopenia and at the onset of clinical signs of lameness from BWE-treated horses and at equivalent times from control horses. Thin sections of laminae were screened for neutrophils by immunohistochemistry with an anti-CD13 monoclonal antibody and extracts of the same tissues were screened for SDS-renaturable and native MMP-9 activities by denaturing and non-denaturing gelatin zymography. Samples were also screened for MMP-2 and MMP-9 gene expression by RT-qPCR. Control laminae were devoid of both MMP-9 and neutrophils, whereas neutrophils and SDS-renaturable MMP-9 activity were detected in laminae from BWE-treated horses and were strongly correlated at the acute stage of the disease at which time laminar MMP-9 gene expression was significantly (15-fold) elevated. In contrast, BWE-treatment did not significantly elevate MMP-2 gene or protein expression in the laminae. Interestingly, MMP-9 that was present in extracts of laminae from BWE-treated horses at both the prodromal and acute stages of the disease was mainly in the zymogen form, suggesting that the accumulation of the MMP did not contribute to pathology during these stages. However, elevated presence of the MMP-9 zymogen in the tissue would predispose it to catastrophic damage should conditions arise that cleave the regulatory propeptide domain.     

Temporal dynamic and economic valuation of recreational fisheries of the lower Cuiabá River,Brazilian Pantanal

Fisheries are the most common ecosystem service that fish provide to human populations, yet recreational fisheries are often overlooked when evaluating such services. Here, the socioeconomic profiles of fishers, the composition of their catches and catch per unit effort (CPUE) are described, to estimate the economic value of the recreational fishery on a stretch of the Cuiabá River in the Brazilian Pantanal. Questionnaires were used to obtain socioeconomic information and fishing yield from fishers for 2013 and 2014. Additionally, a census on the number of fishers and fishing platforms along the sampled region was conducted in 2018. This recreational fishery mostly involves middle class adult males, based mostly in the Cuiabá city metropolitan region. They invested, on average, US$41.1 (SD = US$16.5, median = $35.2) per fishing visit, catching around 19 fish species. Overall, mean CPUE from the recreational fishery was 42.20 fish/fisher.day (17.4 kg/fisher/day). Annual economic value of this recreational fishery was estimated at around US$1.8 million, which highlights the importance of this activity to the local economy. Greater environmental conservation efforts are recommend to ensure the long-term viability of this ecosystem service.     

Plant-species richness in corridor intersections: is intersection shape influential?

Corridor intersections constitute nodes that can be more mesic than the intersecting corridors themselves. Such microclimatic conditions may lead to an “intersection effect,” in which plant richness is higher in the intersection than in the corridors. We hypothesized that an additional factor contributing to intersection effects is the movement of plants along corridors into intersections by way of bird- and mammal-dispersed seeds. If this hypothesis is correct, one would expect intersection-shape effects, defined herein as differences in intersection section richness associated with the number of possible avenues for plant influx into the intersection. Specifically, richness in intersections should be lowest for L-shape intersections (two avenues), higher for T-shape intersections (three avenues), and highest for X-shape intersections (four avenues). We used data from fencerow networks to test this hypothesis about corridor intersections. During October 1992 and March 1993, we determined woody- and herbaceous-plant richness for 25 intersections and their associated fencerows in central Texas, USA. We compared two measures of intersection richness among the three intersection shapes: richness of plants dispersed primarily by birds and mammals (vertebrate-dispersed plant richness), and richness of plants dispersed primarily by wind, ants or other means (non-vertebrate dispersed plant richness). Vertebrate-dispersed plant richness differed significantly among intersection shapes, but no differences in nonvertebrate dispersed plant richness were evident, which is what one would expect if the number of avenues for vertebrate vectors into an intersection was an important factor influencing intersection richness. The intersection-shape effects we found were not attributable to fencerow features (amount of woody cover, width, pressence of breaks) or intersection characteristics (amount of woody cover, size, distance to nearest connected intersection or patch). Our results from fencerow networks support the hypothesis that intersection effects on plant richness are influenced by intersection shape via the number of intersecting corridors. Understanding patterns and processes that occur in networks is important for conservation biologists because intersections in networks have the potential to function as refugia for plant species that require conditions more mesic than those of the surrounding matrix. Networks also may be valuable asin situ sources of seed for managers attempting to restore plant communities in the matrix.     

Spatial scale influence on longterm temporal patterns of a semi-arid grassland

Longterm (45 years) temporal data were used to assess the influence of spatial scale on temporal patterns of a semi-arid west Texas grassland. Temporal basal area dynamics of common curlymesquite (Hilaria belangeri (Steud.) Nash) collected from permanent plots within two areas that were released from disturbance (longterm overgrazing and drought), were evaluated at two spatial scales (quadrat, site). Wiens (1989) proposed hypotheses to characterize the influence of scale on variability, predictability, and equilibrium. These hypotheses were tested for this grassland and temporal patterns observed were different for each spatial scale. The large scale (site) was characterized by low variation between units, high variation within units, high potential predictability, and possible movement toward a fluctuating but relatively stable or equilibrial state. At the small scale (quadrat), variation between units was high, predictability low, and there was no indication of movement toward a stable state; chaotic behavior may be expressed at this scale although the length of the temporal record may not be sufficient to evaluate this phenomenon.     

Birds in North American Great Lakes coastal wet meadows: is landscape context important?

Landscape context can influence species richness, abundance, or probability of patch-use by birds. Little is known, however, about the effects of landscape context on birds in wetland-dominated landscapes. This lack of knowledge is alarming because many wetlands are threatened by development and other human impacts, while serving critical functions as migratory, breeding and foraging habitat. To address this lack of knowledge, we censused birds in North American Great Lakes coastal wet meadows located along the northern Lake Huron shoreline in Michigan (USA) during 1997 and 1998. Using a suite of multivariate techniques, we first accounted for effects of area and within-patch habitat characteristics before testing for effects of landscape context. Most bird variables were significantly related to landscape context, and two major patterns were apparent. First, avian species richness, abundance, and probability of patch-use by some species were higher for wet meadows located in complex contexts (adjacent to many patch types) compared to simpler contexts (adjacent to only one patch type). Second, these variables were higher for wet meadows located in wetland contexts compared to contexts that were terrestrial and road-impacted, dominated by open water habitats, or dominated by forested wetland habitats. Conservation plans for wetlands have focused on saving large wetlands and creating the vegetative habitat structure required by birds, but they should go further and explicitly consider the landscape context of wetlands as well. Specifically, wetlands located in complex and/or wetland contexts should have a higher conservation value than similar wetlands located in simpler, more terrestrial contexts. This revised version was published online in August 2006 with corrections to the Cover Date.     

Behavior of class-level landscape metrics across gradients of class aggregation and area

Habitat loss and fragmentation processes strongly affect biodiversity conservation in landscapes undergoing anthropogenic land use changes. Many attempts have been made to use landscape structure metrics to quantify the independent and joint effects of these processes. Unfortunately, ecological interpretation of those metrics has been plagued by lack of thorough understanding of their theoretical behavior. We explored behavior of 50 metrics in neutral landscapes across a 21-step gradient in aggregation and a 19-step gradient in area using a full factorial design with 100 replicates of each of the 399 combinations of the two factors to assess how well metrics reflected changes in landscape structure. Metric values from real landscapes were used to determine the extent of neutral landscape space that is represented in real landscapes. We grouped metrics into three major behavioral classes: strongly related to focal class area (n=15), strongly related to aggregation (n=7), and jointly responding to area and aggregation (n=28). Metrics strongly related to class area exhibited a variety of distinct behaviors, and many of these metrics have unique interpretations that make each of them particularly useful in certain applications. Metrics strongly related to aggregation, independent of class area, are particularly useful in assessing effects of fragmentation. Moreover, metrics in this group exhibited a range of specific behaviors, highlighting subtle but different aspects of landscape aggregation even though we controlled only one aspect of aggregation. The non-linear behavior exhibited by many metrics renders interpretation difficult and use of linear analytical techniques inappropriate under many circumstances. Ultimately, comprehensive characterization of landscapes undergoing habitat loss and fragmentation will require using several metrics distributed across behavioral groups.This revised version was published online in May 2005 with corrections to the Cover Date.     

URETERAL DIVERTICULA IN TWO DOGS

We describe ureteral diverticula in two dogs and briefly review the related literature. The diagnosis of this condition is radiographic and based on the excretory urographic observation of multiple ureteral outpouchings. Pathologically, ureteral transitional cell hyperplasia and mucinous metaplasia result in submucosal proliferation of the urothelium and the formation of crypts and small cysts. Ureteral diverticulosis in humans is associated with an increased risk of urothelial malignancies, such as transitional cell carcinoma of the urinary bladder. Clinically, both dogs were older, small breed neutered females. Both had a history of chronic urinary obstruction. One dog died during surgery to remove an adrenal mass, and the other was euthanized at the owner's request because of an inoperable bladder neoplasm. Histopathologic diagnosis of ureteral lesions confirmed the radiographic diagnosis of ureteral diverticula in both dogs.